In the production of a pharmaceutical composition of non-viable cell preparations in the form of a solution or a suspension, such as cell lysates, problems are often encountered with aggregation, flocculation and/or sedimentation. This problem causes inhomogeneity in the product, leading to qualitative or quantitative inconsistencies, particularly in case the product has to be dispensed over multiple containers. In addition, it may cause lack of homogeneity between multiple batches of the product.
For example, in the production of a wound healing composition such as a keratinocyte cell lysate, and in particular cultured human keratinocyte cell lysates, rapid aggregation, flocculation and partial sedimentation of the cell lysate contained in these solutions or suspensions is observed after the homogenization (lysis) steps in the production process. Such aggregation, flocculation and/or sedimentation results in lack of homogeneity in the solution or suspension of the cell lysate and further complicates its processing, in some cases, this can even render the composition unusable for its intended purpose. Thus there is a need for modifications that can aid the processing step before or after homogenization by preventing flocculation or sedimentation.
It is well known that chemical agents stimulate flocculation or aggregation of proteins leading to precipitation. U.S. Pat. No. 4,565,635 describes a water soluble chemical agent “xanthan gum”, known to function as a flocculating adjuvant Similarly U.S. Pat. No. 3,956,519 describes a process in which aggregation of a protein in aqueous solution is induced by dissolved debranched low-DE maltodextrin or debranched amylopectin.
In the pharmaceutical sector, xanthan gum is utilized in the manufacturing of freeze dried pharmaceutical tablets as described in the WO Application No. 9501782 in which xanthan gum facilitates suspension of the granular therapeutic agents in the liquid admixture and does not have any adverse affects on the dispersion qualities and texture of the tablet upon usage.
On the contrary U.S. Pat. No. 6,010,719 describes use of xanthan gum as a thickening agent, which increases viscosity of the suspension and is suitable for preventing sedimentation of the solid drug particles. Similarly, xanthan gum has also been used to suspend large biological particles for the purpose of stabilizing cell suspensions during flow cytometry, thereby preventing sedimentation (Cytometry 10: 803-806 (1989)). Another example shows that the presence of xanthan inhibited the aggregation and demixing of whey protein isolates and resulted in a homogenous mixture (Food Hydrocolloids 12: 469-479 (1998)).
All these examples however apply to relatively simple intact suspensions of cells or specific proteins.
Cell lysates, on the other hand, result from the lysis of cells, which releases many components in various forms, forming an extremely complex mixture of constituents such as proteins, glycoproteins, polysaccharides, lipids, nucleic acids etc. All these components may interact with each other, significantly increasing the possibility for complex formation and flocculation, ultimately resulting in a non-stable solution or suspension and sedimentation of part of these components.
Accordingly, it can be seen that there remains a need to provide a homogenous stable pharmaceutical composition comprising cell lysates. One example of such a composition contains a keratinocyte cell lysate, which is suitable for wound healing purposes. There further remains a need to provide such pharmaceutical composition of cell lysates in the form of a solution or a suspension, which are homogenized and if required further processed by drying or freeze-drying.